In the early days of television when a viewer wanted to see what the selections of programming were, he would manually change from one channel to the next by turning a knob on the television set. This was a reasonable thing to do because originally there were only a few channels among which to choose. Cable TV brought an increase in the number of available channels and the accompanying technology of the remote control, which gave the viewer the capability to surf through the channels until he came upon a program that he wanted to watch. With the advent of satellite TV, and the corresponding leap from dozens to hundreds of channels of available programming, came the need to provide the viewer with a more convenient means for making program choices.
Paper guides listing channels and times of programming are printed in the newspaper and elsewhere but these are inconvenient and difficult to use, thus the development of electronic programming guides (EPGs). EPGs are lists of programming information displayed on the television screen or monitor which provide an interactive method for the viewer to review options and make programming choices.
In most EPGs known in the art, when a viewer wants to select a program, the EPG presents a list of available programs, typically in the form of a text list. The viewer is able to select the type of program, the time slots and other parameters in order to customize the program listings displayed and limit the choices to a reasonable number. In some cases, the text may have an additional small picture or logo pertaining to a specific item in the list of programs. For example, an image of a football may appear, referring to a listed football game or an image of a bat and ball may refer to a listed baseball game.
A drawback to the prior art EPGs is that knowing the name of the program, even with other information available in the textual format, may not be enough information to really inform the viewer of her choices. In this age of reruns and syndication, different episodes of the same show may be playing on the same day at different times or even on different channels at the same time. Just knowing the name of the show may not be enough to know if the program is an episode the viewer wishes to see. Also, with so many programming choices from which to draw, the viewer cannot possibly be acquainted with the name of every program. It would be useful to be able to see in real time what is currently showing on the selected channels and thus to receive quick impressions of the programs currently in progress when making a viewing choice.
One way of providing this kind of real time information is to create thumbnail video scenes for display on the video screen or monitor. “Thumbnail” is a term used by graphic designers meaning a small image representation of a larger image. Displaying thumbnail images of scene choices allows more choices to be displayed more quickly and manageably than using full size images.
The technology to generate a thumbnail of a video stream is known in the art. In standard broadcast television, for example, the approximate video resolution of the video stream is 600×400 pixels. In contrast, the thumbnail video resolution is much lower, typically only 20×16 pixels or so. In the prior art, broadcast providers generate live thumbnail video streams for multiple channels at the head-end and combine them into a fixed array of thumbnails which are made available to viewers in a single video stream broadcast over a separate preview channel. The fixed array of thumbnails is then capable of being displayed as a standard mosaic of live thumbnail videos.
One drawback to combining thumbnails into a fixed array at the provider head-end is that providers supply so many channels that only a small number of them can be combined into any particular array, typically up to 16 channels per array. But those 16 channels may not be the ones which the viewer is interested in previewing. Another drawback is that the use of a separate preview channel to supply the thumbnails wastes bandwidth. At the receiving end there is yet another drawback—the EPG cannot provide the viewer with the ability to select only certain thumbnails for display from the fixed array. Because the fixed array of thumbnails is encapsulated using standard video transport protocols, there is no way to identify the content of each individual thumbnail. Consequently, all of the thumbnails represented in the fixed array must be displayed on the preview channel as a predetermined mosaic of live thumbnail streams.